Optically excited microwave impedance microscopy
a microwave impedance and microscopy technology, applied in the field of material measurement systems, can solve the problems of inconvenient use, fragile, complex, etc., and achieve the effect of reducing the spatial resolution of optical techniques, and avoiding the use of sensitive instruments
- Summary
- Abstract
- Description
- Claims
- Application Information
AI Technical Summary
Benefits of technology
Problems solved by technology
Method used
Image
Examples
first embodiment
[0031]In the invention illustrated in FIG. 1, a light source 80 outputs a beam through optics 82 to irradiate a portion of the sample 18 surrounding the probe tip electrode 14. In one embodiment, the light source 80 is temporally modulated by a modulating electrical source 84 through a light source controller 88. For infrared absorption, the light source 80 is preferably a tunable infrared laser outputting a laser beam at selectable wavelengths in the 3 to 12 micrometer range as controlled by the light source controller 88 under the direction of the system controller 20.
[0032]The frequency of the modulating source 80 and indeed its waveform can be widely chosen depending upon the configuration of the rest of the system. Its frequency or other time characteristic may be used to demodulate the detected microwave signal. The modulation frequency may be off the resonant cantilever frequency, for example 100 kHz, although other frequencies may be chosen, for example 10 kHz to 500 kHz but...
second embodiment
[0044]Carrier lifetime is an important measure of the quality of a semiconductor. Its measurement with nanoscale resolution of the semiconductor structure would be highly informative. In the invention, FIG. 3 illustrates a block diagram of an optically excited lifetime microwave microscope system 90. Most of its parts have been described with reference to FIG. 1. However, the temporal modulation of the laser light source 80 is pulsed with a pulse width ranging, for example, from 10 ns to 10 ms and controlled by trigger generator 92 connected to the light source controller 88 through a closed switch 94 on a line 96. Once the laser light source 80 has irradiated the sample 18 and particularly after the light pulse has ended, two data acquisition units 98, 100 are triggered by the trigger generator 72 to sample the I and Q outputs of the microwave circuitry 42 to provide a time profile of these signals. Their decay times after the light pulse are indicative of the lifetimes of the elec...
third embodiment
[0046]the invention, illustrated in the simplified block diagram of FIG. 4 for an optically driven microwave microscope system 110, is fundamentally electrically passive and does not require that a microwave signal be electrically applied to the sample. The output of the laser 80, preferably tunable in the range of 1500 to 800 cm−1, having an infrared optical frequency fIR, is modulated in an optical modulator 112 according to a microwave reference signal from the microwave source 40 operating at fMW, which may be 3 GHz. The infrared range is centered at about 10 μm so that the optical or infrared signal frequency fIR is about 4 orders of magnitude greater than the microwave frequency fMW. The optical modulator 110 produces a signal which is the product of the optical and microwave signals which has two sidebands at frequencies fIR±fMW.
[0047]The optics 82 focus the modulated beam including its sidebands to an area of the sample 18 surrounding the electrode tip 14 and typically to th...
PUM
Login to View More Abstract
Description
Claims
Application Information
Login to View More